Frothing agents for use in froth flotation processes



Patented Aug. 24, 1954 FROTHING AGENTS FOR USE IN FROTH FLOTATI ON PROCESSES Roger F. Powell, Gwel 0, Southern Rhodesia, and

Eric F. Martin, Germiston, Transvaal, Union of South Africa; said Martin assignor to said Powell No Drawing. Application June 13, 1950, Serial No. 167,912 7 Claims priority, application Great Britain June 14, 1949a- Claims.

This invention relates to froth flotation processes for the concentration of noble and base metal ores and their products and other material amenable to such processes and it has particular reference to frothing agents used in carrying out such processes.

A major feature of this invention is the provision of a wide range of frothing agents for use in place of the commonly employed steam-distilled pine oil and other frothing agents already known, from which range of frothers a selection may be made as may best suit the wide and variable nature and composition of the materials to be treated by flotation processes.

The invention provides improvements in processes of the above kind using as is well understood, any usual promoting reagents such as for instance xanthates, with if desirable, any usual well-known conditioning reagents such as acids, alkalis, salts and so forth, by replacing the wellknown frothers such as pine oil, cresols, higher alcohols and so on, by a single member, a fortuitous mixture, or a pre-arranged blend, of a very wide range of related organic compounds (excluding sulphur or nitrogen) as hereinafter indicated.

In the said range of related compounds, there are very wide variations of properties, ranging from straight froth-producing substances. through frother-collectors, to collector-frothers. Because of the wide variation of properties, and because virtually all the individual compounds are mutually miscible, it has been found practicable to provide a single compound, or a blend, ideally suited to the particular requirements of any particular industrial flotation process.

The related compounds above referred to comprise firstly alkoxy substituted acyclic hydrocarbons, the unsubstituted hydrocarbon containing from 4 to 10 carbon atoms, being substituted with from 4 to 6 alkoxy groups, having no more than one disubstituted alkoxy grouping at a terminal carbon atom of said hydrocarbon, the alkoxy groups being connected to the hydrocarbon by a CO-C ether linkage and being selected from the group consisting of methoxy, ethoxy, normal propoxy, isopropoxy, methoxy-ethoxy and ethoxy-ethoxy; secondly alkoxy substituted acyclic straight chain hydrocarbons containing from 4 to 10 carbon atoms in the hydrocarbon chain and substituted with from 3 to 5 alkoxy groups and one divalent oxygen, the alkoxy substituents being connected to the hydrocarbon chain by a 0-0-6 ether linkage, having no more than one disubstituted alkoxy grouping at a terminal carbon atom of said hydrocarbon, and being selected from the group consisting of methoxy, ethoxy, normal propoxy, isopropoxy, methoxyethoxy and ethoxy-ethoxy.

To give one striking example in connection with the properties of such compounds, those compounds whose properties rate them as pure frothers are usually found to give excellent recoveries of easily fioatable minerals such as chalcocite, but if such compounds are used on an ore-containing tarnished pyrite, or pyrrhotite, the froths are still'of an excellent type, but only a small proportion of the latter minerals reports in, the froth. On the other hand, those compounds whose properties rate them as frother-collectors, are still found to give excellent recoveries of the chalcocite, but in the case of tarnished pyrite, it is found that a very large proportion of the latter mineral reports very rapidly in the froth, as is implied by the term frother-collector.

Certain of the compounds have the collecting property very highly developed, at the expense of the straight frothing property. The mineral reports veryrapidly but the froth hangs back in the machine. A good example of this is the tetra-ethyl-ether of pentaerythritol. In such cases blending-in some of a straight-nothing compound overcomes the difiiculty.

Certain of the compounds have a very pronounced collecting power, and give strong froths, but there is a tendency for the condition of overoiling to appear; the remedy being to blend-in a compound of different characteristics. This tendency to over oil appears to be connected with an unbalanced molecular structure, where the hydrocarbon portion of the molecule is not sufiiciently balanced by enough alkoxy substituents. Contrasted with the latter, is the type represented by 1:2:3:4 tetramethoxybutane and 1:2:3:4:5:6 hexamethoxyhexane. Both of these tend to give rather shallow wattery brittle froths; and it is considered that the alkoxy substituents are here in excess. The compound of intermediate structure, 111:3:5 tetramethoxyhexane has much better properties.

Some of the compounds which may be used according to the present invention, are solids at room temperature. However, they function quite satisfactorily if the crystals are slowly added to the ore-pulp or the like. Where such method may be industrially impracticable, the crystals may be' dissolved in a small quantity of one of the liquid compounds.

It has become clear that the possible permutations and combinations of flotation properties in the wide range of compounds comprised in the definition here given, are extremely numerous. Actual flotation examples hereinafter set forth are accordingly intended to demonstrate that:

(i) As widely difierent classes of compounds are herein proved it may be reasonably assumed that the whole range according to this invention has a distinct value in flotation processes; and

lvlethoxy CHsO- Ethcxy G1H O Normal Propoxy CH3. 0112.01123- Isopropoxy CH3. ([331. CH;

| Methoxy-E thoxy C H; O .C'Hz. C H2O- Ethoxy-Ethoxy OKs-C1120 CH2.CH--

wherein symbol Y denotes double-bonded oxygen and symbol Z denotes hydroxyl:

(i) At least two monovalent substituents X shall necessarily be attached by the C-O-C (ether) linkage to at least one or more carbon atoms in any of the straight-chain, branchedchain or monocyclic structures set out below.

(ii) More than two substituents X are allowable; some very valuable compounds have four substituents and several have been tested that have six, and it is believed accordingly that more than six are admissible. 7

(iii) In addition to the substituents X, the divalent substituent Y above, may be attached to any single carbon atom. More than one substituent Y may be present.

(W) In addition to the substituent X, the monovalent substituent Z above, may be attached to any single carbon atom. More than one Z substituent maybe present.

(V) Y and Z substituents may not be attached to the same carbon atom.

The molecular structures above referred to, are exemplified as follows, it being assumed that all free valencies on all carbon atoms are satisfied by hydrogen atoms except where the substituents as X, Y and Z are attached:

('1) Stmight chain.Four up to ten carbon atoms CCC-C 8L0.

(ii) Branched chain.-From four to ten carbon atoms.

(a) 'SuchJfor instance as isopentane -c-cc-c I (b) The type represented by neopentane (iii) Any of the above structures (i) and (ii) 4 in which two adjacent carbon atoms are linked by an unsaturated double bond C=O.

The following examples of structural types, the subject of tests already made, illustrate the wide range of organic compounds which possess frothing or frothing-collecting properties:

throughtheseries up 0:

NEI-

Before reference is made to tabulations of results of tests made with a wide variety of organic compounds, it is convenient to summarize the essential properties of frothers of interest in froth flotation processes, when used in conjunction with any of the commonly known promotors and/or conditioners, as follows:

i. That a small quantity of the frother per unit quantity of the ore or other material treated shall suflice to obtain the desired effect.

ii. Rate of dispersability of the frother in an aqueous ore or like pulp to which it is added.

iii. Carrying or collecting powera term already understood in the art.

iv. Selectivity of the frother in its action upon the diiferent minerals or other substances in association with one another in the pulp or the like, each of which having to be floated and, as far as possible, floated separately.

v. Selectivity of the frother in its action as between minerals or other materials which it is desired to float, and gangue or the like which it is desired not to float.

vi. Persistence of the frother in recirculation.

More particularly when straight-chain compounds are used such may be a polyalkoxyparaflin comprising from a single carbon atom to six carbon atoms in the paraffin chain (or up to carbon atoms in the chain in certain cases) with from 4 to 6 or more alkoxy groups attached by the carbon-oxygen-carbon or ether linkage in any positions on the paraflin chain; the said alkoxy groups being methoxy, ethoxy, normal propoxy or isopropoxy, methoxy-ethoxy, ethoxy-ethoxy, or a mixture of said alkoxy groups.

Dialkozcy par fi'ins. Although a number of these compounds are found to be technically effective, they are weaker frothers than pine oil, for example, the dialkoxyparaflins:

1:1 d-iethoxybutane H H E 002115 H--(J-C-t'J-H H H CaHs and 1 :1 diisopropoxyethane Trialkoxyparafflns other than 1:1:3 triethoxybutane as mentioned in my Patent No. 2,561,251, have shown marked differences in behaviour as for example 1:1:3 trimethoxybutane, 1:1:3 tri- Methoxy (-OC3) Ethoxy (-OCzI-I5) Propoxy (OC3H7) efiective Methoxy-ethoxy Ethoxy-ethoxy Butoxy (-OC4H9) Pentoxy (-OCsI-In) Position 0 alkoxy groups It has been discovered that the position of the three alkoxy groups attached to the atoms of the paraflin chain is not of the utmost importance. Thus, 1:1:3 triethoxypropane of formula?- difiering only from the 1:123 triet'hoxybutane by having one less carbon atom in the paraffin chain was investigated and proved highly effec-. tive, although other differences were found which render the selection of the butane as preferable.

Compared to this 1:213 triethoxypropane displayed properties very close in all respects to those of 1:1:3 triet'hoxypropane, compare:

The above discovery coupled with another set out hereinafter regarding the effectiveness of polyalkoxY-Dfiraffins in which the alkoxy groups are attached in the 1:1:2:2 position:

2 x E n s. x x supports the conclusion that the positioning of the alkoxy groups on the carbon atoms of the parafiin chain is not a vital factor.

On the foregoing reasoning it is considered that the polyalkoxyparafiin will be effective when the paraflm contains from 4 to 10 carbon atoms and is substituted with alkoxy groups in the alpha, beta, or gamma positions in relation to one another, e. g. where X represents an alkoxy group:

& Gamma x 7, or in specific cases 1:1;414 gamma-tetra-methoxy-butane, andl12'23 2.4 tetra-methoxybutane.

Efiect of nature of alkory group It was found by experiment on the following compounds namely:

Trimethoxypropane Triethoxypropane Tripropoxypropane Trimethoxybutane Trieth'oxybutane Tripropoxybutane Tributoxybutane Tripentoxybutane Tetra-ethoxyethane Tetra-propoxyethane 'Ietra-butoxyethane In the case of polyalkoxyparafilns having more than 4 carbon atoms in the parahin chain it has been found from tests on (a) 111:3 triethoxyhexane of formula and on (b) the substance 1:113 triethoxyoctane that these compounds are extremely efiective with properties differing from the related triethoxypropane and triethoxybutane showing clearly the relationship between properties and the number of carbon atoms in the paraffin chain. Thus in the case of triethoxymethane of formula it has been found that this extreme member of the series of triethoxyparafiins is weak but perfectly effective and its observed properties fall in the deducible place in the series from the singlecarbon methane to the S-carbon hexane.

GENERAL Supported by results of further tests, the conclusion has been reached that all polyalkoxyparaflins within the range already indicated in an earlier part of this specification, and more particularly set out below, are effective flotation frothers with flotation properties varying in accordance with the following variables:

1. Number. of carbon atoms in the parafiin chain from 4 to or even more.

ii. Number of alkoxy groups attached to the paraffin chain from 4 to 6.

iii. Nature of the alkoxy group.

Limited to methoxy, ethoxy, normal propoxy, isopropoxy, methoxy-ethoxy and ethoxy-ethoxy.

Adverting to the question of properties of any irother, upon which depend its effectiveness in flotation processes, the following further observations are made in relation to the use or the polyalkoxyparafiins above discussed:

8 No. 1.Quantity needed per ton of ore or coal to produce desired efiect (a) The greater the number of alkoxy groups the less is this quantity, other structure of the molecules being equal.

(b) The greater the number of carbon-atoms in the paraffin chain, other structure of the molecule being equal, the less is this quantity.

(0) The particular alkoxy group selected from the possibles, namely methoxy, ethoxy, normal propoxy and isopropoxy, very markedly affects this property; generally, increasingly smaller quantities are required per ton of ore or the like as the series is ascended:

0 CH3, 0 C2H5, O C3117 but occasionally methoxy-ethoxybehaves very much the same as ethoxy-.

N.0. 2-Rate at which the (water-insoluble) frother disperses in the aqueous ore-pulp The tetraalkoxyethanes have been observed to disperse extremely rapidly, and an increase in the number of alkoxy groups appears to have no appreciable efiect on this property.

It appears that G-carbon atoms in the chain determines the practical limit on this property. It has been observed also that this property appears not to be substantially affected by change F in the nature of the alkoxy group employed.

1:1:3 triethoxyoctane (B-carbon) is rather slowerdispersing than 121:3 triethoxyhexane but is a practicable commercial substance when used alone.

No. 3--Carry'ing or collecting power This property, which though nearly is not strictly the inverse property to property No. 1 above:

(a) Increases as the number of carbon-atoms in the parafiin chain, this increase being very clear and definite;

(b) Is affected only slightly by changes in number of alkoxy groups;

(c) Increases very definitely, other structure of the molecule being equal, in the series- Methoxy, ethoxy, isopropoxy, and normal propoxy No. 4..S'electiuity as between two or more va uable minerals which are required to be floated as far as possible separately (12) This property, other structures of the molecule being equal, decreases very materially in the direction methoxy, ethoxy, n-propoxy, and isopropoxy, that is to say the property is in inverse ratio to property 3 above;

(b) This property is substantially unaffected by the number of alkoxy groups attached in the chain;

(c) This property depreciates, that is selectivity decreases, with increase in the number of carbon atoms in the parafiin chain.

No. 5-Tlte deleterious tendency to float valueless gangue with valuable minerals, or the like (a) This property seems to be especially troublesome when insufficient alkoxy substituents in this regard are- 1 1 :3 triethoxyhexane and 1:1:3 triethoxyoctane On the other hand, this property seems to be absent from 1:2:3:4:5:6 hexa-methoxyhexane, and we believe that in this latter case the efiect of the 6 alkoxy groups has overcome it. On many ores this property is not very serious, but in the case of base metal flotation, it is an important one, so that a definite limit has to be set in selecting a suitable species of frother. As is well known the flotation of a relatively larger amount of gangue can be tolerated when treating sulphide gold ores for the reason that the gold content will be extracted not by smelting the whole concentrate but by wet lixiviation methods; so that the limit of five-carbon chains does not apply, in fact the six-carbon 1:1:3 triethoxyhexane has been proved by test to be an extremely efiective frother on sulphide gold ores.

(b) The property again increases markedly as between the ethoxy and the isopropoxy groups, other structures of the molecules being equal, and decreases as between ethoxy and methoxy, but less markedly.

No. 6.-Persistence of frother in water recirculated to head of circuit In commercial practice this is a very valuable property already recognised in the art. From visual and other observations the following conclusions are reached:

(a) Whereas this property is possessed in a marked degree by polyalkoxyparaflins containing methoxy 01' ethoxy groups it is possessed to a less marked degree in 1:1:3 triethoxyhexane than in the other ethoxy compounds; and it appears to become less marked when treating ores containing unusually high colloid contents. Polyalkoxyparaffins containing isopropoxy groups appear largely devoid of this property, while normal propoxy groups bring about a total deficiency in this property;

(11) 1:1:2:2 tetraethoxyethane possesses the property in a marked degree.

From the foregoing it appears that species which show this property do so by reason of a lesser degree of adsorption upon the minerals and gangue, compared with pine oil, for example, and that species containing isop-ropoxy groups and/or long parafiin chain species may be of little interest per se in processes of certain kinds.

The following three tabulations of data support the foregoing correlation of molecule structure within the range of this invention with the more important of the flotation properties above discussed which are briefly outlined for case of reference to the tables:

Mineral selectivity varies inversely as the molecular weight of the alkoxy group and inversely as the length of the parafiin chain.

Mineral-carrying power (collecting-power) varies directly as the molecular weight of the alkoxy group. Iso-propoxy confers very much increased collecting-power compared with normal-propoxy. It also varies directly as the length of the parafiin chain.

"Quantity needed, per ton of ore or coal, to produce desired effect, decreases very markedly as the number of alkoxy groups increases, as the number of carbon atoms increases from two to four, except when the four alkoxy groups are attached in the 1:2:3z4 position; and also as the 10' alkoxy series rises through methoxy, ethoxy, isopropoxy.

Deleterious tendency to float valueless gangue varies directly both in the ascending series methoxy, ethoxy, to isopropoxy-n-propoxy and as the length of the parafiin chain.

TESTS Fourteen tests were carried out in a 2,000-gram Denver-Fahrenwald Flotation Machine, under rigidly standardised conditions.

The only variable introduced was the different substance used as frother in each case; the quantity added was the same in each case, namely one standard capillary drop at the start of flotation, followed by four standard capillary drops after removing the primary concentrate for two minutes; an exception was made in two special tests, where only one drop was added after removing the primary concentrate.

The ore was of an ordinary type, largely quartzitic, with a natural alkalinity of pH 9.2; the two minerals present were a barren -chalcopyrite and an auriferous pyrrhotite. Grinding was to 62% minus 200-mesh.

Earlier research, had demonstrated that the pyrrhotite is peculiarly sensitive to adequate carrying power of the frother; accordingly the standard conditions for the tests were so selected that the ,Control Test just did not give optimum recovery of the pyrrhotite.

The results set out in Tables I, II and III, give full details of the tests carried out. It should be noted that the Lbs. Pyrrhotite in Residue are, under the standard test conditions inversely proportional to the carrying-power, or collectingpower of the frother tested.

Additional to those shown in the tabulation, the following other polyalkoxyparafiins were tested, and found to have only. slight value as frothers.

with the three most important flotation properties.

TABLE I.MINERAL SELE CTIVITY re ca e Ratio 1st 0011 Test Pytrhotite Frotlier Used to ohalco Pyrrho- Chaloopyrite tite pyrite 19 1:1:3 Trimethoxypropane 40. 9 69. 2 .59 to 1 20 Triethoxymethane 49. 8 69. 5 .72 to l 19 1:223 Triethoxypropane 57.7 72. 2 .80 to 1 l3 1:1:2:2 Tetraethoxyethane 58. 9 67.3 .87 to l 8 'Comml. Triethoxybutane--. 63. 5 70. l .90 to 1.

14 1:1:3 Triethoxypropane 60. 8 66. 4 .91 to 1.

21 1:1:3 Triisopropoxypropane. 79.4 75. 5 1.05 to 1. 16 1:1:2:2 Tetra-n-Propoxy- 76. 6 69. l 1.11 to 1.

ethane. l0 1:1:2:2 Tetraisopropoxy- 88.2 62. 2

ethane. 1.31 to 1 T--.-..-.----.-. as 22-1 r e oxy exane 11 do 98.3 68.8

TABLE II.MINE RAL-OARRYIN G POWE R (Collecting Power) TABLE HI.--DELETERIOUS TENDENCY TO FLOAT VALUELESS GANGUE Percent Gangue inand. Con. g Frotlier Used V First 0011. st Frother 19 111:3 Trhnethoxypropane 13.1 20.6 1:223 'lriethoxypropane. 13. 2 27. 6 Triethoxymethane 21.9 20.9 1:1:2z2letraethoxyethane- 15.2 31.8 1:1:3 Triethoxypropane 15.2 32. 8

Oomml. Triethoxybutane 18.3 31. 7

111:2:2 Tetraisopropoxyet-hane 23. 8 60. 9 12' 25.8 41.1 9 121:3 Triethoxyhexane 22.4 58.2 11 24.9 46.1

Adverting to the feature that organic compounds embraced within the wide range herein set forth and utilizable individually as effective frothing agents, are readily miscible with one another with the important result that means are thereby afiorded in flotation practice enabling the frother by selective mixture to be varied in such a way as to combine in desired proportion essential properties each possessed by the individual substances in difierent degrees to suit special characterisation of a given ore, coal or other material to be treated, this aspect of the present invention will now be more fully discussed.

From a knowledge of the particular flotation properties of individual species in the wide range of compounds herein set forth, blends of any two or more of these substances can be produced with predictable flotation properties.

Advantages accruing from the aforegoing are very substantial, as. will appear from the following wherein, for convenience, straight-chain compounds alone are dealt with:

1. Large quantities of cheap species can be blended with smaller quantities of expensive species for economic reasons;

2. Species, one or other of whose properties exclude or substantially exclude them from the range of practical efiectiveness when used alone, can be combined to bring such properties within the useful range by intelligent blending of such species with one another, for example:

(a) The six carbon polyalkoxyhexanes are so slow in dispersing in the ore-pulp or the like as.

generally to be unacceptable in practice. It is possible to blend a six-carbon hexane compound with a three carbon polyalkoxypropane compound so as to provide a blend better than the ingredients. The same remark applies to those species comprising more than six carbon atoms in the chain, which disperse at an even lower rate, appropriate blending overcoming this fault. Other properties, such, for instance, as strength of the polyalkoxyhexane constituent of the blend will not be destroyed by thus blending.

(b) The lower members of the series, such, for instance, as triethoxymethane and even some, at least, of the dialkoxypararfins, which latter are comparatively cheap, can be brought into the range of practical utility by blending a suitable proportion of one of the more effective members of the series containing 4 or more alkoxy groups, and/or five or six or even more carbon atoms in the paraffin chain.

The possibilities arising from blending as explained may further bring into the range of practical utility as frothers, species up to decaalkoxydecanes, that is with carbon atoms up to 10, and with alkoxy groups up to 10 attached, for example, 1:1:3:5:'7:9 hexamethoxydecane:

OHQO C1130 H CHaO CHaO CHaO H H i. Selectivity as between two or more valuable minerals which are required to be floated as far as possible separately This property of selectivity is substantially inversely proportional to collecting-power, a fact which opens up wide possibilities in the result of blending suitably selected compounds.

ii. Deleterious tendency to float nameless gangue with valuable minerals It has already been established that this tendency is proportional to the number of carbon atoms in the paraffin chain and is also specifically possessed by those species in which the alkoxy group is isopropoxy. Also there is little, if any, increase in this deleterious property as one increases the number of any specific alkoxy groups in the molecule.

For the flotation treatment of particular ores and the like, specific frothers may thus be produced by blending suitable members of the series having regard to the foregoing. As is well known, three main types of ore are met with, namely (a) Gold ores in which a comparatively small percentage sulphides or arsenides individually rich in gold require to be concentrated by flotation, in which case the desideratum is maximum recovery of these auriferous minerals, while the floating oi. a little extra gangue can be tolerated.

(b) Bulk flotation of one or more minerals of one base metal, e. g. copper, in which case while maximum economic recovery isnaturally highly tages obtainable by the use of frothing agents obtained by selective admixture of two or more 13 14 desirable it is absolutely essential that -the mini- TABLE IV MINERAL OARRYING POWER mum of siliceous gangue shall be present 1n the (8mm gth) final concentrate.

(c) Ores in which minerals of two or more base Pep metals are to be separated as far as possible from r cent. coach other as well as from the gangue; in which Test No. Frothers Used 5%;; fi case the desiderata are extreme selectivity couleft 1 pled with deep and powerful froth while at the same time maximum carrying-power is desired a I in the second or final stage of flotation. Test 2.... {fiig ii gfiggggggg fi }'Iotal 3.. 33.6 76.9

As regards coal separation the first desideratum (i e. 1:1 vol. mix) is extreme selectivity to permit the separation of Test gggg 2 two or more basic types of coal, as for instance, Test {1:1:3 Triethoxyhexane 1. I} g d n gn coal. (1. e. 321 V0]. mix) The following examples illustrate the advan- 15 TABLE V.TENDENOY T0 FLOAT VALUELESS GANGUE polyalkoxyparaflins in accordance with the pres- Percent ent invention. 15225? Gangue Tests were carried out in rigidly standardized lfif mothers Used conditions using the well known promoting 1 t 2 d reagent 301 at a natural pH of 8.0 in a standard 3 5 2,000 gram Denver-Farenwald flotation machine.

The ore used contained 150 lbs. per ton pyrf- Test 3.. 1=1=3 Triethoxyhcxane 1 1 28.7 42.4 hotite and 13 lbs. per ton of chalcopyrite and con- T t 1 2 {1 2&8 4L3 tained a rather unusually large prop rti n of 1. 3 vol n ixf 1 reactive true colloid. Test 2..- re 1 2 35.2 42.

Standard tests using pine oil as frother have ESfiiitti? {1} 5 given very poor results. It had been established by experience that each and all of the numerous TABLE VI tested polyalkoxyparaifins were completely miscible with each other. Lb t l r The results set out in Tables IV, V and VI, are omi'f fgtfi ifi based upon two specific blends of frothers and Test No of 0011' fitfg they illustrate how (First test) 1:2:3 triethoxy No. Fromm Used Drops to propane whose properties used alone 'made it Pyr- 01ml i i?? unsuitable for sulphide gold ores has been con 3%; .verted into a frother of great effectiveness for such ores by blending in the substance 1:1:3 tri- Comml. Triethoxyhexane in the proportion of 1 volume of the 40 Test 2... .P %Q$fg, 1 28.34 10. 77 2.63 to 1. latter to, 3 volumes of the former; and how '(Sechexane. 2 0nd test) by mixing equal volumes of 1:1:3 trigg glg 1% ethoxybutane with 1:1:3 triethoxyhexane the Test Tri'ethoxv- 2 38'96 348w resultant blend was such that three standardized Test 1 J5 IL 70 3'82) 1 volumes gave 76.9% recovery of the valuable hexane 7 a 1 mineral pyrrhotite while 4 standard volumes of 1:1:3 triethoxybutane only gave 61.3% recovery; Further test results embracing the use of while another test (test No. 3) usingpure 1:1:3 numerous representative organic compounds triethoxyhexane gave the intermediate figure 67.1 using only two standard volumes.

within the scope of this invention are now appended as Tables VII toX inclusive.

TABLE VII standardised, strictly comparative, flotation tests in a 2,000-gran1 ing approximately 16.8 dwts. Ace. and the Frother as stated, at start. stated. 5 minutes froths designated as Denver-Fahrenwald machine on a old chalco it Grind 45 minutes with 4 grams lime and 0.30 gram copper suilphatg. pyr pyrrhotlte' ore assay 2 minutes froths designated as First Cons.

Then 0.25 gram of the same xanthate, and the Frother as Second 0011s. Residual pulp washed out of machine, designated as Tallings.

Products Percent Weight Assays of Products (15235: no; S ulphur) Percertageloi Total Dwt. assay ulp ur Test No Percent Sulphur Gold 1st 2nd Tall- Cons. Cons. ings 1 t 2 d s n 1st 2nd Cal. 1 t Cons Cons Tallmgs Tailings Cons Cons Tallmgs Ore s gg 7. 03 6. 22 86. 75 30. s. 74 3. s2 s7. 64 2s. 2s- 7 7. 75 3. 22 s9. 03 27. 19 12 s 39' 5 7. l3 6. 27 86. 60 30. 07 30 6 19 4 7. 00 6. 25 so. 75 29. 66 30' 7 20' s s. 92 6. 37 86. 71 27. 05 33' 9 17 s 6.16 6.72 87.12 19.88

0.10 gram Sodlum-sec-butyl xanthate Quantity of Substance added Test No. Substance used as Frother Remarks 1st 2nd Con. Con. Total 7 cc. cc. cc. PXX l Commercial 111:3 Triethoxybutane .028 042 070 Control =test: Froth a little water, hut'active. Persistent. 'PX'X2 1:1:3 Trimethoxybutane .056 .084 .140 Extremely active and strong. Highly persistent. A smaller quantity would havesuificed. PXX3 1:2:3:4 Tetramethoxybutane. .064 .090 .160 wzi ak vzatgry and shallow. Clearly larger quantity needed.

. ersis en 4 {1:2z3z4:5:6Hexamethoxyhexane. 056 084 140 A mixture of 71% of the First Substance and 29% the second.

' 1:2:3:4:5,Hexamethoxyhexanol. All characteristics very similar to Control Test." PXX 6 A high molecular-weight hi .032 .048 .080 .Frothstough and gummy: non-persistent. Intense flocculation ethoxylated paraflin of unknown of mineral. Resins" present. detail composition.

PXXQ Ethyl-Beta-Ethoxy-Crotonatc .030 .045 .1075 Just liquid at room temperature. Conditioning time about 1 as fortPine Oil. Very strong, deep, active iroths. Very 'pcr- .sisten PXX 10 1:1:3 Triethoxyoctane .014 .028 .042v Conditioning time rather longer than for Pine Oil. intensely mineralized smell-bubble froths, with a tendency to over-oil" even in this very small uantity.

TABLE VIII.-A CHALOOPYRITE-PYRRHOTITE OR-E -Lbs. Valuable Min- Percent Recovery Product Mineral Grade 0f Product eral Per Ton Ore Mineral Percent- Substance tested as Frother Product Wageht P t P t .Pemem e1" ercen ercen Value- Ghalco- Pyrrho- Ghalco- Pyrrhoof Ore Chalco- Pyrrho- I pyrite me Gelsgsue I pyrite tlte pyrite tits 4. 13. '1 55. 5 31. 4 l0. 9 46. 1 83.1 35. 5 5. 22 0. 8 641.5 .34. 7 0.8 67. 4 6. 5 52. 0 1.1.5.5 Tetra-E thoxy-Pentene 9.37 6.2 60.5 33.3 11.7 113.5 89.6 87. 5 (Pure), 0.028 cc. 90. 63 0. 08 0.81 1. 4 16. 2 Calculated Ore 100. 00 Q. 65 6.49 '13. 1 129.7 1st C0110 3. 85 13.9 50. 7 10.7 39. l 81. 5 28. 8 2nd C0110 5. 28 1. 3 63. 7 1. 4 67. 3 10. 5 49. 5 PincOil (Steam Distilled), 0.076cc Combined Cones" 9. 13 6. 0 58:2 12. 1 106. 4 92.0 78. B Residue 90. 87 0. 06 1. 62 l. 1 29. 5 Calculated Ore.- 100. 00 0. 66 6. 79 13. 2 135. 9 1st Cone 3. 24 19. 1 51.4 12. 4 33. 3 86. 2 22. 6 2nd C0110 5.15 1. 6 66. 5 l. 6 68. 5 l1. 2 46. 7 1.1.2.2 Tetra-Ethoxy-Ethane, .051 cc- Combined Cones" 8. 39 8. 3 '60. 7 14. 0 101. 8 97. 4 69. 3 Residue 91. 61 0. 03 2. 53 0. 4: 45. 6 Calculated Ore 100. 00 0. 71 7. 37 14. 4 147. 4

N0'rE.-ln all three tests the Iroths were excellent, though the pine oil frother was less persistent than the other two. Note the collecting property, on the mineral ethoxy-ethane.

TABLE IX.--STANDARD pyrrhotite, of the 111:5:5 tetre-ethoxy-pentane, as-compared to the lack of collecting property oi the 121:2:2 tetra- FLOTATION TESTS ON A CHALCOPYRITE-PYRRHOTITE ORE IN A 2,000 GRAM LAB. MACHINE Lbs. Mineral Kareem Mineral Grade of Products Per Ton ore Substance used as Frother Froduct Wfeight Froth type v o re ggi gg' gg?" Gangue Chal. Pyrr.

1st Gone- 3.87 14. 0 38. 7 47. 3 10. 9 29. 9 0.014 cc. for 1st. con. was H H 5. 94 0. 5 61.1 38. 4 0.5 72. 6 slightly too little. Mids X. 1. HCCC--C 9.81 5. 8 52. 3 41. 9 l1. 4 102. 5 very deep, active and H 90. 1Q (l. 09 l. 86 1. 5 33. 6 persistent.

0 (Ellis Gael. Ore 100 0. 64 6. 80 12.9 136. 1 O C2H betajbeta diethoxy butyrate (0.042

O C 2H5 O C2H5 112 CH: 1st Cone 3.15 15. 6 49. 8 34. 6 9. 8 31. 4 A dead type hanging back 3. 1. 8 68. 8 29. 4 1. 2 44. 7 in cell. Collecting X. 3. C 6. 40 8. 6 59. 5 31. 9 11.0 76.1 power is, however, there.

93. 0.08 3. 27 1. 4 e1. 2 H20 (EH2 100 0. 62 6.87 12. 4 137. 3

tetra ethyl ether of pentaerythrltol 3.86 13.1 48. 7 38. 3 10. l 37. 6 Ablencl of of the latter with 20% 2. 94 1.3 71. 5 27. 1 0. 8 42.1

of Commercial Triethoxybutane 6. 80 8.0 58. 5 33. 5 10.9 79. 7 Normal. (0.060 00.). .3. 2O 0. 09 3. 25 l. 7 60. 6 100 0. 63 7. O1 12. 6 140. 3 C .3. 13. 9 5g. 7 H11; 33.13 2nd onc 5.28 1.3 6 .7 6 'steam'dsnned Pm Comb. 00:10---. 9.13 6. 6 58.2 12.1 105. 4 Do.

Residue 90. 87 0. U6 1. 62 l. 1 29. 5 C810. Ore 0. 66 '6. 79 13. 2 135. 9

ORATORY 'ras'rs rN'aooo- ORY GOLD-COPPER ORE GRAM FLOTATION Grade of Product Percent Valueless Gangue Product Percent Chalcopyrite 7 Percent Pyrrhotite Test 9 Test 16 Test 17 Test 9 Testlfi Test 17 Test 9 Test 16 Test 17 7-minute Concentrate 7. 48 8. 69 8. 32 53. 93 62. 27 60. 66 38. 59 29. 04 31.02 Residue 0. 038 0.038 0. 029 2. 970 1. 892 2. 533 Calculated Ore Feed 0.677 0. 753 0. 717 7. 343 6.851 7. 372

Test 9 Test 16 Test 17 Gold left in Residue: per ton ore ieed .Q. 1. 21 1.15 1.15

Lbs. Mineral/Ton Ore in Product Percentage Recovery of Mineral Product Ohalcopyrite Pyrrhctite Ghalcopyrite Pyrrhotite Test 9 Test 16 Test 17 Test 9 Test 16 Test 17 Test 9 Test 16 Test 17 Test 9 Test 16 Test 17 7-minute Concentrate.- 12. 84 14. 36 13.97 92. 54 102. 87 101. 79 94. 8 95. 3 I 92. 4 63.0 75.1 69. Residue 0. 70 0.70 0. 37 54. 32 34.15 45. 64 5. 2 4. 7 2.6 37. 0 r 24. 9 31.0 Calculated Ore Feed 13. 54 15. 06 14. 34 146. 86 137. 02 147. 43 100 100 100 100 100 100 Test 9 Test 16 Test 17 Sodium-sec-butyl Xanthate added: 0. 35 0.35 Frother added: 4

" 0551f I II "I 0:052. 0.051 0 047 Actual weight Concentrate Percent Weight concentrate Actual weight Residue" Percent Weight Residue. Actual weight Ore Feed. Percent Weight Ore Feed.

1 1 2:2 Tetra-(Mcthoxy- 1 Ethoxy)-Ethane.

REMARKS 1. Clearly the (methoxy-ethoxy)- substitucnt in a paraffin confers properties very close to those conferred by ethoxy-.

2. This is remarkable, seeing that difierences between methoxy-, ethoxy-, isopropoxy-, and butoxyhave been found to be very eat. gr 3. In spite of the fact that the molecular weight of the compound, the strengths of the two are very similar (1. e. quantity Yet 121:5:5. tetra-ethoxy-Pentane is the strengt is proportional to the length of the paraifin chain.

4. Both viscosity and density are clearly greatly increased by the presence of the (methoxy-ethoxy) We are aware that the use of certain alkoxyparaiflns in flotation processes forms the subject of one or other of Union of South Africa patent applications Nos. 2,197/48 and. 2,709/48, these applications corresponding to U. S. Patents Nos. 2,561,251 and 2,591,289 in the joint names of the applicant R. F. Powell herein, and others.

What we claim is:

1. A method for concentrating minerals by flotation comprising the steps of adding to the mineral pulp a small quantity of an alkoxy substituted acyclic hydrocarbon as a frother, the unsubstituted hydrocarbon containing from 4 to 10 carbon atoms, being substituted with from 4 to 6 alkoxy groups, having no more than one disubstituted alkoxy grouping at a terminal carbon atom of said hydrocarbon, the alkoxy groups being connected to the hydrocarbon nucleus by a C-O-C etherlinkage and being selected from the group consisting of methoxy, ethoxy, normal propoxy, isopropoxy, methoxy-ethoxy and ethoxy-ethoxy, and thereafter subjecting the resulting mixture to a flotation operation.

2. A method for concentrating minerals by flotation comprising the steps of adding to the mineral pulp a small quantity of a frother which is an alkoxy substitute acyclic straight chain hyquite three times as strong as ei nee (methoxy-ethoxy)-compound is 326, vs. 206 for the corresponding ethoxyded to give same flotation results). ther, though its molecular weight is only 248. Obviously -substituent.

' ing mixture to a flotation operation.

3. A method for concentrating minerals by flotation comprising adding a frother to a mineral pulp, said frother being a member of the class consisting of an alkoxy substituted'acyclic hydrocarbon, the unsubstituted hydrocarbon containing from 4 to 10 carbon atoms, being substituted With from 4 to 6 alkoxy groups, having no more than one di-substituted alkoxy grouping at a terminal carbon atom of said hydrocarbon, and an alkoxy substituted acyclic straight chain hydrocarbon containing from 4 to 10 carbon atoms in the hydrocarbon chain and substituted with from 3 to 5 alkoxy groups and one divalent oxygen, the alkoxy substituents being connected to the hydrocarbon chain by a COC ether linkage, having no more that one (ii-substituted al- 1.9 koxy grouping at a terminal carbon atom of said hydrocarbon, and being selected from the group consisting of methoxy, ethoxy, normal propoxy, isopropoxy, methoxy-ethoxy and ethoxy-ethoxy and thereafter subjecting the resulting mixture to a flotation operation.

4. A method for concentrating minerals by flotation comprising adding to a mineral pulp a small quantity of beta,beta diethoxy ethyl butyrate as a, frother and thereafter subjecting the resulting mixture to a flotation operation.

5. A method for concentrating minerals by flotation as claimed in claim 1 comprising adding to a mineral pulp a small quantity of hexa methoxy decane as a frother and thereafter subjecting the resulting mixture to a flotation operation.

6. A method for concentrating minerals by flotation as claimed in claim 1 comprising adding to a mineral pulp a small quantity of an alkyl ester of a diethoxy substituted fatty acid as a frother and thereafter subjecting the resulting mixture to a flotation operation.

'7. A flotation method as in claim 3 wherein a blend of different irothers each in accordance with the frother formulation of claim 3 is employed.

8. A method as in claim '7 wherein one of said frothers in the blend is a solid substance and the other of said frothers is a liquid substance.

9. A method as in claim 3 wherein the frother is a tetra alkyl ether of pentaerythritol.

10. A method as in claim 3 wherein the frother is a 1,2,3,4 tetra alkoxy butane.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,902,070 Halbig Mar. 21, 1933 2,561,251 Van Aardt July 17, 1951 2,591,289 Powell et a1 Apr. 1, 1952 OTHER REFERENCES Milling Methods for 1930, by American Institute of Mining and Metallurgical Engineers, pp. 307 to 357. (Copy in Div. 25.) 

3. A METHOD FOR CONCENTRATING MINERALS BY FLOTATION COMPRISING ADDING A FROTHER TO A MINERAL PULP, SAID FROTHER BEING A MEMBER OF THE CLASS CONSISTING OF AN ALKOXY SUBSTITUTED ACYCLIC HYDROCARBON, THE UNSUBSTITUTED HYDROCARBON CONTAINING FROM 4 TO 10 CARBON ATOMS, BEING SUBSTITUTED WITH FROM 4 TO 6 ALKOXY GROUPS HAVING NO MORE THAN ONE DI-SUBSTITUTED ALKOXY GROUPING AT A TERMINAL CARBON ATOM OF SAID HYDROCARBON,AND AN ALKOXY SUBSTITUTED ACYCLIC STRAIGHT CHAIN HYDROCARBON CONTAINING FROM 4 TO 10 CARBON ATOMS IN THE HYDROCARBON CHAIN AND SUBSTITUTED WITH FROM 3 TO 5 ALKOXY GROUPS AND ONE DIVALENT OXYGEN, THE ALKOXY SUBSTITUTENTS BEING CONNECTED TO THE HYDROCARBON CHAIN BY A C-O-C ETHER LINKAGE, HAVING NO MORE THAT ONE DI-SUBSTITUTED ALKOXY GROUPING AT A TERMINAL CARBON ATOM OF SAID HYDROCARBON AND BEING SELECTED FROM THE GROUP CONSISTING OF METHOXY, ETHOXY, NORMAL PROPOXY ISOPROPOXY, METHOXY-ETHOXY AND ETHOXY-ETHOXY AND THEREAFTER SUBJECTING THE RESULTING MIXTURE TO A FLOTATION OPERATION. 